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Home >> Audi >> 1998 >> A6 Wagon (4A5) V6-2.8L (AHA) >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Component Tests and General Diagnostics >> Signal From A/C Compressor

Signal From A/C Compressor



Required special tools and test equipment
- VAG 1551 or VAG 1552 Scan Tool (ST) with VAG 1551/3 adapter cable
- VAG 1598/22 test box
- Multimeter US 1119 (Fluke 83 or equivalent)
- VW 1594 connector test kit
- Wiring diagrams

Test conditions
- A/C functions OK
- A/C is switched off
- Vehicle at room temperature: above 15 °C (59 °F)
- No malfunctions stored in Diagnostic Trouble Code (DTC) memory.

Checking
- Connect VAG 1551 or VAG 1552 scan tool and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (with engine running at idle).

Indicated on display

Rapid data transfer HELP
select function XXX

- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08, and press -Q- button to confirm input.

Indicated on display

Read Measuring Value Block HELP
Input display group number XXX

- Press buttons -0-, -5- and -0- to input display group number 50 (050), and press -Q- button to confirm input.

Indicated on display (1-4 display fields)

Read Measuring Value block 50 ->
1 2 3 4

- Switch on A/C using the "AUTO" button. Verify compressor is running.

- Compare display with specified values for A/C (in display field 4).





NOTES:
- The A/C compressor is switched off during acceleration when the car is stationary or at slow speed.
- At wide open throttle the A/C compressor is switched off by the Transmission Control Module (TCM) (via the kick down switch).

Continuation
If the displayed values are NOT OK:
- Connect VAG 1598/22 test box to ECM harness connector.
- Check wiring for open circuit, short circuit to B+ or short circuit to Ground between ECM/test box terminal 8 and either A/C control head -E87- or Transmission Control Module (TCM).

If the wiring is OK:
- Check function of A/C control head -E87-.
- Carry out electrical testing of automatic transmission. Refer to Transmission Control Systems, On Board Diagnostics (OBD). Testing and Inspection
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconcerted, generate new readiness code.



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